With some creative repurposing (and some extra lengths of 4040 from Amazon), I used this kit as a base for my flight sim cockpit. The end result is stable and nicely customizable--I was able to get everything within an inch or two of the 152 cockpit I used as a reference.
The only minor difficulty I encountered was removing the alignment tabs from the corner brackets. The easiest method I found is to hold a flathead screwdriver against the base of the tab at about a 45 degree angle and give it a solid whack with a hammer. The tab should shear right off.